1.1 本试验方法包括通过测量衰减率来测量混响室中的吸声量。描述了测量房间吸收、物体（如办公屏幕）吸收和吸声材料（如吸声天花板）样本吸声系数的程序。 1.2 现场测量- 尽管本试验方法涵盖了实验室测量，但本规范中所述的试验方法 4.1 可用于对房间的吸收进行现场测量（另请参见 5.5 ). 试验方法中描述了测量现场房间吸收的方法 E2235 . 1.3 本试验方法包括实验室认证信息（见 附件A1 )，不对称屏幕（参见 附件A2 )和混响室鉴定（见 附件A3 ). 1.4 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 5.1 房间吸声测量是其他声学测量程序的一部分，例如确定噪声源的声功率级或隔墙的声传输损耗。它还用于某些计算中，例如当房间中噪声源的声功率级已知时，预测房间中的声压级。 5.2 表面的吸声系数是组成表面的材料的特性。理想情况下，其定义为表面吸收的随机入射声功率的分数，但在本试验方法中，其在操作上定义为 4.2 . 理论定义系数和操作测量系数之间的关系正在继续研究。 5.3 衍射效应 5. 通常会导致试样的表观面积大于其几何面积，从而增加根据本试验方法测量的系数。当试样具有高度吸收性时，这些值可能超过1。 5.4 使用本试验方法测得的系数应谨慎，因为实际使用中不仅遇到的面积通常大于试样，而且声场很少漫反射。 在实验室中，必须在可再现的条件下进行测量，但在实际使用中，确定有效吸收的条件通常是不可预测的。无论差异和判断的必要性如何，建筑师和顾问已成功地将这种测试方法测得的系数用于建筑空间的声学设计。 5.5 现场测量- 当在房间大小和形状不受操作员控制的建筑物中进行吸声测量时，扩散声场的近似值不太可能非常接近。在评估现场条件下测量的准确性时，应考虑这一问题。（见试验方法 E2235 对于可在现场使用不太复杂仪器的程序。 )

1.1 This test method covers the measurement of sound absorption in a reverberation room by measuring decay rate. Procedures for measuring the absorption of a room, the absorption of an object, such as an office screen, and the sound absorption coefficients of a specimen of sound absorptive material, such as acoustical ceiling tile, are described. 1.2 Field Measurements— Although this test method covers laboratory measurements, the test method described in 4.1 can be used for making field measurements of the absorption of rooms (see also 5.5 ). A method to measure the absorption of rooms in the field is described in Test Method E2235 . 1.3 This test method includes information on laboratory accreditation (see Annex A1 ), asymmetrical screens (see Annex A2 ), and reverberation room qualification (see Annex A3 ). 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== 5.1 Measurement of the sound absorption of a room is part of the procedure for other acoustical measurements, such as determining the sound power level of a noise source or the sound transmission loss of a partition. It is also used in certain calculations such as predicting the sound pressure level in a room when the sound power level of a noise source in the room is known. 5.2 The sound absorption coefficient of a surface is a property of the material composing the surface. It is ideally defined as the fraction of the randomly incident sound power absorbed by the surface, but in this test method it is operationally defined in 4.2 . The relationship between the theoretically defined and the operationally measured coefficients is under continuing study. 5.3 Diffraction effects 5 usually cause the apparent area of a specimen to be greater than its geometrical area, thereby increasing the coefficients measured according to this test method. When the test specimen is highly absorptive, these values may exceed unity. 5.4 The coefficients measured by this test method should be used with caution because not only are the areas encountered in practical usage usually larger than the test specimen, but also the sound field is rarely diffuse. In the laboratory, measurements must be made under reproducible conditions, but in practical usage the conditions that determine the effective absorption are often unpredictable. Regardless of the differences and the necessity for judgment, coefficients measured by this test method have been used successfully by architects and consultants in the acoustical design of architectural spaces. 5.5 Field Measurements— When sound absorption measurements are made in a building in which the size and shape of the room are not under the operator's control, the approximation to a diffuse sound field is not likely to be very close. This matter should be considered when assessing the accuracy of measurements made under field conditions. (See Test Method E2235 for a procedure that can be used in the field with less sophisticated instrumentation.)